Sensory Aspects of Respiratory Symptoms Flashcards
Describe the pathway from stimulus to evoked sensation? What are the names for the two main parts of this?
Stimulus - transducer - excitation of sensory nerves - integration of CNS - sensory impression
This is NEUROPHYSIOLOGY
Sensory impression - perception - evoked sensation
This is BEHAVIOURAL PSYCHOLOGY
Describe the distribution of rapidly adapting irritant receptors within the airway epithelium.
They are most numerous on the posterior wall of the trachea and in the main carina.
They decrease in number as you go down the airways and they are absent in the bronchioles.
They are commonly found at the branch points of large airways.
What are the three main types of sensory receptors in the lungs and airways?
C-fibre receptor
Slowly adapting stretch receptors
Rapidly adapting stretch receptors
Which nerve do all the sensory receptors in the lungs and airways pass through?
Vagus nerve
What is used as a stimulus for the C-fibres?
Caspaicin
What stimulates C-fibres?
Chemicals
What do the rapidly and slowly adapting stretch receptors respond to?
Inflation (increase in tracheal pressure)
Describe the differences between the three types of sensory receptor.
C-fibres are unmyelinated whereas the other two are myelinated.
C-fibres are found in the larynx, trachea, bronchi and lungs
Rapidly adapting stretch receptors are found in the naso-pharynx, larynx, trachea and bronchi
Slowly adapting stretch receptors are located on airway smooth muscle, mainly in the trachea and main bronchi
What are the two broad types of sensory receptor in the airways?
Mechanoreceptors
Nociceptors
Other than mechanical displacement, what else activates the mechanoreceptors?
Citric acid
What is the collection of neurons in the cough centre called?
Nucleus tractus solitarius
What is this collection of neurons connected to?
Medullary cough pattern generator
What is the role of the cerebral cortex in the complete cough pathway?
The cerebral cortex is needed to generate a cough and generate the urge to cough. When asleep, this component of the complete cough pathway is inhibited so a certain degree of wakefulness is needed to cough. General anaesthetic also inhibits this.
What are the three phases of cough?
Inspiratory phase
Glottic closure
Expiratory phase
What is acute cough and what is it usually caused by?
Cough that lasts less than 3 weeks
It is commonly caused by rhinovirus
What are the causes of chronic cough?
Asthma Gastrooesophageal reflux Rhinosinusitis Chronic bronchitis Bronchiectasis
What is another name for chronic cough? How can the sensitivity be tested?
Cough hypersensitivity syndrome
Giving patients increasing concentrations of caspaicin until they cough. People with cough hypersensitivity syndrome will have relatively low tolerance of caspaicin.
What drugs can inhibit the cortical control of the cough reflex?
Opiates
Sensory perception from the nose and the pharynx goes through which nerves?
Nose - trigeminal
Pharynx - glossopharyngeal and vagus
Describe the anatomical pathways of touch and pain.
Touch and pain differ in the level at which they cross over to the other side of the spinal cord.
Touch crosses over at the level of the caudal medulla
Pain crosses over immediately
What is the clinical significance of this?
Brown-Sequard Syndrome
What’s the difference between somatic and visceral pain?
Somatic pain is easy to localise
Visceral pain is difficult to localise
There are fewer visceral afferents than somatic afferents
What scale is used to grade dyspnoea?
Modified Borg Scale
What are the three types of dyspnoea?
Air Hunger
Tightness
Work/Effort of breathing
